Known stage lighting fixtures comprise a main body extending along a longitudinal axis; a light source housed inside the closed end of the main body to emit a light beam substantially along the axis; and light beam filtering and/or modelling means positioned to intercept the light beam.
The light beam filtering and/or modelling means are designed to produce special beam effects, and normally comprise light beam colouring assemblies; gobos; and a zoom device for adjusting the size of the image projected by the lighting fixture.
The ever increasing need to reduce the size of stage lighting fixtures makes it necessary to minimize the size of the light beam filtering and/or modelling means and, therefore, also the zoom device.
Known compact zoom devices, however, are invariably deficient in terms of quality and efficiency.